1. Field
One or more embodiments described herein relate to a light-emitting display device and a method for fabricating a light-emitting display device.
2. Description of the Related Art
An organic light-emitting display has a relatively wide viewing angle, high contrast, and fast response speed. Each pixel of this display includes an organic light-emitting layer between an anode and a cathode. When positive and negative voltages are respectively applied to these electrodes, holes move from the anode to the organic light-emitting layer via a hole injection layer and a hole transport layer, and electrons move from the cathode to the organic light-emitting layer via an electron injection layer and an electron transport layer. The electrons and holes recombine in the organic light-emitting layer to generate excitons. When the excitons change from an excited state to a ground state, light is emitted. The light emitted from the pixels generates an image.
The organic light-emitting display may include a pixel defining layer having an opening that exposes the anode. The hole injection layer, hole transport layer, organic light-emitting layer, electron transport layer, electron injection layer, and cathode may be formed on the anode exposed through the opening in the pixel defining layer.
The hole transport layer and the organic light-emitting layer may be formed as thin layers using an inkjet printing method or a nozzle printing method. These methods may use an ejector to eject a solution into the opening of the pixel defining layer. During the inkjet printing method, a material to be printed may be applied at a desired location in the form of ink droplets. During the nozzle printing method, a material to be printed at a desired location is made to flow along a line including the desired location.
A lyophilic pattern may be formed on the anode in order to increase wettability of a hole transport solution.
When a hole transport solution is ejected onto the lyophilic pattern using the nozzle printing method, force generated from air current created by the fast moving speed of the ejector may push the hole transport solution to one side of the lyophilic pattern. As a result, the hole transport solution may dry to have a non-uniform shape. This may cause the display to have non-uniform emission characteristics, and thus reduced display quality.
If the hole transport solution pushed to one side overflows to an adjacent pixel, the hole transport layer may be formed in part of the adjacent pixel. In this case, the organic light-emitting layer on the hole transport layer may also be formed in the part of the adjacent pixel. Therefore, organic light-emitting layers that emit light of different colors in adjacent pixels may overlap each other. This may cause an unwanted mixing of different color light, which also reduces display quality.